OBAMA PRESIDENTIAL CENTER

UHPC Structural Screen Wall Facade Panels: Stainless Steel Fiber

Tod Williams and Billie Tsien Architects (TWBTA) and Heintges approached Fine Concrete in early 2019 to consult on the feasibility of using UHPC to achieve the inspired design of a double-sided façade screen wall for the Obama Presidential Center.

The screen consisted of 458 cast letters, each 4’-4” tall spelling out President Barack Obama’s speech at Selma in 2015. TWBTA designed two 84’ tall by 67’ wide screens wrapping the corner of the 225’ tall main tower and cantilevering off the structure with only three levels of support and no visible connections. After exploring several material options and fabricators, the design team determined that UHPC was the preferred material and Fine Concrete was the design fabricator to realize this vision.

Fine Concrete engaged Silman Engineers from the beginning of the conceptual design phase to assist in the structural solutions to achieve this design. Silman analyzed and engineered 39 unique panels as structurally spanning elements, eliminating the need for a backup frame system. Using cutting edge modeling and software to meet the design team’s intent, Silman was able to work within the geometry of the letters to resolve the complex loading. With a stainless steel design mix, Silman optimized the UHPC material for thinner panels, using less material and reducing the structural load and embodied carbon. Fine Concrete is the only UHPC fabricator in North American to have constructed multiple projects using stainless steel fibers in a mix created by Holcim and developed with them over 5 years in close collaboration.

Fine Concrete designed molds and a fabrication strategy that fit within the Center’s aspiration for sustainable design. Instead of routing 39 disposable forms, and sending mountains of Styrofoam to the landfill, Fine Concrete designed the largest letterpress ever made and a system of fiberglass reusable letter forms. When combined with unique blockouts and reusable space bar forms we were able to assemble the formwork for all 39 panels using just 52 reusable letter forms. After intensive iterations to ensure seamless panels, the concept was proven in a mockup cast by Fine Concrete in 2020 and erected on a site near the Presidential Center. For the final molds, Fine Concrete used a unique combination of robotic manufacturing, large-scale 3d printing and hand craftsmanship to produce a kit of parts for the panel castings in our shop in Virginia.

To achieve the other project goals of utilizing local Chicago labor and lowering the carbon footprint of transportation, Fine Concrete entered into a partnership with Envel Facade as a casting partner less than 100 miles from the project site.

Fine Concrete is very honored to have had the opportunity to contribute to this landmark project, and excited about the innovations we have made in UHPC fabrication and design.

Design: TWBTA

Fabrication Design, System Design and Mold Making: Fine Concrete

UHPC Engineer: Silman Associates, Washington D.C.
Casting: Envel

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